Liquid shock absorber for motorcycle forks



CL 21, 1941- R. scHLElcHER A 2,259,589 I LIQUID SHOCK ABSORBER FOR MOTORCYCLE FORKS Filed Ngv. 1, 1958 ifffffff. \\\N\\\ :IIIIII Patented Oct. 21,

' UNITED yjs'rmlizs .PATENT OFFICE w 259.589

LIQUID snocx Ansoaaaa Foa MOTORCYCLE Foaxs l Rudolf Schleicher, Munich, Germany, assignorto v the iirm Bayerische Motoren Werke Aktiengesellschaft. Munich, Germany Application November 1,.193s,seriaiNo.z3s,1so In Germany November 16, 1937 ,13 claim.

This invention relates to a fluid shock absorber, and. more particularly to one which is adapted for use with a vehicle, such forexample, as a motor cycle.

An object of the invention is the provision of an improved shock absorber.

Another object of this'invention is a shock absorber which may be easily and quickly mounted and removed from a vehicle.

A more specific object of this invention is the provision of an improved shock absorbing and springing device for motorcycle forks.

With these and incidental objects in view, the invention consists in certain novel features of construction and combination of parts which are set forth in the appended claims, a preferred form of embodiment whereof is hereinafter described with reference to the drawing which accompanies and forms part of the specification.

` An example of construction-of the invention is shown diagrammatically in the accompanying drawing, wherein: Y

Fig. 1 shows avertical section of a fork sheath in the hollow space of which there is shown in elevation a liquid shock absorber according to the invention; and

to provide v vDuring the Vupward movement of the lower fork tube 3 with the shock absorber tube I and guide member 6, there is produced, by the suction action of the latter, above the stationary valve I0, a certain negative pressure by which the valve is drawn in and opened up to the stop pin I3. The space between' the two valves Ill and I4 is made smaller by the upward movement of the lower fork tube 3 with the shock absorber tube i, and the liquid located above the Valve Il is forced through the valve i0. By the downwardvmovement of' the fork4 tube 3 withthe absorber tube I and guide member 6. the pressure of the latter onthe liquid column serves to close the upper valve Ill, and the liquid is forced slowly through the bore l of the guide member 6 along the piston rod 8, whilst the damping of the rec'oil takes place, which can be adjusted according to the selection in diameter of differently large bores I in the guide member 6. Underneath the valve I0 a certain negative pressure is produced in the absorber tube I, whereby the lower valve I4 is opened and fresh liquid is again sucked in from the fork tube 3 from the bores l5. The liquid which collects above the edge of the absorber tube I and then runs along bore l of which there is guided a piston rod lof y which the upper end may be rigidly connected to the spring member through a closure screw 3, whilst at its lower end a valve I0 and a guide plate I I are held by suitable means such as a nut l2. A pin I3 or other suitable means in the piston rod 3 serves to prevent the valve l0 from being opened too far. A second valve I4 is provided near the bottom of the tube I and underneath this valve, bores i5 for the' admission of the damping liquid are provided in the shock absorber tube. The closure screw ,3 forms the closure for the upper opening of the stationary fori:` tube I6, whereby the piston rod 3 with the upper valve i0- and the guide plate Ill forms the stationary part of the shock absorber, and theA tube i with the guide piece l the movable part which follow.

this back into the storage tank ofthe lower fork tube 3. In this manner a constant circulation of the shock absorbing liquid takes place, whereby only a very small quantity of this liquid is necessary.

WhileV the shock absorber above described is particularly suitablefor use in connection with motorcycle forksit is obvious that the construction is not limited to this alone, but may be used in any manner where a readily releasableshock absorber is desired. v

. Accordingly, while. it be noted that the con struction shown and 'described will serve admirably to accomplish the objects stated above,

as various modifications thereof may' be made without departing from tho invention as designed by aproper interpretation" ofthe claims The guide plate II is provided at its port, means for guiding the outer tube on said intermediateV tube for relative sliding movement and preventing relative movement thereof in the radial direction, means for rigidly interconnect- .ing the inner and outer tubes to said wheel support, a` concentric piston rod connected to said frame structure and mounted inside said inner tube, a shock-absorbing fluid Within said tube, a iirst valve means on the'end of said piston rod for permitting ow of said uid in the upper direction only. and second valve means permitting the iiow of said iiuid from said outer tube to said inner tube.

2. The combination according to claim 1, in combination with springing means intermediate said outer tube and said'frame. 3. In a vehicle having'a frame, a wheel supporting member, and shock absorbing means for said wheel supporting member, comprising, in combination, three substantially .vertical concentric tubes, the intermediate one of which is rigidly interconnected with said ing the outer tube on said intermediate tube for relative sliding movement and preventing relative movement thereof in `the-radial direction, means `for rigidly interconnecting the inner and outer tubes to said wheel supporting member, a concentric piston rod connected to said frame and mounted inside said inner tube, a shock absorbing fluid in said tubes, a guide plate provided with a grooved peripheral surface, connected to the end of said piston rod, 'a first valve means lmounted on said guide plate for permitting ow of said fluid in the upper direction only, means for limiting the movement of said valve,and second valve means permitting flow of said uid from said outer tube to said inner tube.

4. In a vehicle `having a trarne.A a wheel supporting member, 'and shock absorber means for resiliently connecting said frame to said wheel supporting member, including a tube closed at its lower end and rigidly interconnected at that end with said'wheel supporting member, a piston rod .depending from said frame inside of and concentric with said tube, a unidirectional valve on the-end of said rod, cooperating with said: tube, means for guiding said piston rod Within said tube with a predetermined substantial amount of clearance to form a dampening throttle, a shock absorbing fluid in said tube, a pair of additional tubes surrounding said iirst tube, closed atvtheir outer ends, and respectively connected to said frame and said Wheel supportingmember, and means for guiding said additional tubes for relative sliding movement while'preventing relative movement in the radial direction.

v5. In a vehicle having a frame, a wheel supporting member, and shock absorber -means for resiliently connecting-said frame to said wheel supporting member including a tube closed at its lower end and rigidly interconnected at that end with said wheel supporting member, a piston rod extending from said frame inside of and concentric with said tube, a unidirectional valve on the end of said rod, cooperating with said tube, means tor guiding saidpiston rod within said tube with frame, means for guida predetermined amount of clearance, a clamping spring for holding said guiding means within said iirst tube, a shock absorbing iiuld in said tube, and a pair'oi' additional tubes surrounding said first tube,'one relatively slidably guided upon the other, closed at their outer ends, and respectively connected to said frame and said wheel supporting member.

which said first tube is 6. In'a motorcycle, a Wheel fork including a frame structure, a wheel support, a pair of tubes, means for guiding said tubes for relative sliding movement and preventing relative movement in the radial direction.. one of said tubes being closed at one end and rigidly interconnected with said frame structure against relative movement, the other of said tubes being closed at one end and rigidly connected-to the wheel support, a third tube mounted concentrically within said pair of tubes, open at one end and closed at its .other end and there connected tothe closed end of one of said pair of tubes, a piston rod connected to the closed end of the other of said pair of tubes, shock absorbing fluid in said tubes, and a one way valve on the end of said rod for permitting flow of said fluid through said third tube in one direction.

7. In a vehicle having a frame, a wheel supporting member, a pair of tubes,- one of which is slidably guided upon the othennne of said tubes being closed at one end and; there connected to the frame, the other of said tubes being closed at one end and connected to the wheel supporting member, a third tube mounted concentrically within said pair'of tubes, open'at one end and closed at its other end and there connected to the closed end of one of said pair of tubes, a piston rod connected to the closed end of the other oi said pair of tubes, a piston rod guide mounted -within said third tube at a slight distance from said piston rod to form a dampening throttle therebetween, shock absorbing iiuid in said tube. and a one way valve on the end of said rod for permitting iiow of said fluid through said'th'irci tube in one direction.

8. The combination according to claim 6, in which said third tube is provided with openingsv near its closed end to permit iiow of iiuid fror within one of saidpair of tubes to within sai third tube.

9. A liquid shock absorberfor interconnecting two relatively movable members, comprising, in combination, a tube open at one end and closed at the other end and rigidly interconnected at the closed end with one of said members, a piston rod mounted on the second member inside of and concentric with said tube, means for-guiding said piston rod within said tube with a predetermined amount of clearance to form a dampening throttle, a uni-directional valve on the end of said piston rod, and 'a pair of additional tubes surrounding said `first tube, pne relatively slidably guided upon the other, closed at their outer ends, andrespectively connected to'sald iirst/and second members. f

10. The combination according to claim 9, in provided with openings near its 4closed end to permit ow of iiuid withinV one of said pair of surrounding tubes within said first tube.

1l. The combination according to claim 9, in

which said rst tube is provided with openings 12. A liquid shock absorber for interconnectl ing two relatively movable members, comprising, in combination, a tube openI at one end and closed at the other end and rigidly interconnected at the closed end withrone of said members, a piston rod mounted on the second member inside of and concentric with said tube, means for'guiding said `piston rod within said l tube with a predetermined amount of clearance, a clamping spring for holding said guiding means within said tube, a uni-directional valve on the end of said piston rod, and a pair of additional tubes surrounding said rst tube, one relatively slidably guided upon the other, closed at their other end, having an integral forked wheeljournal' support descending from said closed end',

and provided with al bore between the fork support in its closed end, and shock absorbing means for said wheel supporting member, including a second hollow cylindrical tube rigidly connected with said frame, spaced means for guiding said i'lrst tube on said second tube for relativelysliding movement, a third hollow cylindrical tube, means rigidly attaching said third tube to said wheel supporting member, concentrically with said rst and second tubes, comprising a plug in the lower end of said third tube, having a threaded extension projecting through said bore of said'rst tube, and a nut rigidly clamping said plug to said wheelsupporting member, a piston rod connected to said frame and mounted concentrically within said third tube, a shock absorbing uid within said tube, a rst valve means on; the end of said piston for permitting ilow in the upward direction only, and second valve means permitting flow of said fluid from said iirst tube to said third tube.

RUDOLF SCHLEICI-IER. 

